Defect detecting method and system for optical disc

Abstract

A defect detecting method for an optical disc accessed by an optical pickup head, including: (a) detecting if any defect exists in a detected region of the optical disc after data is written to the detected region; (b) while writing data to the optical disc, detecting if any defect exists on the optical disc according to reflection from the optical pickup head to thereby generate a first defect detecting result; and (c) switching from one of the steps (a) and (b) to the other of the steps (a) and (b).

1 . A defect detecting method for an optical disc accessed by an optical pickup head, comprising:
 (a) detecting if any defect exists in a detected region of the optical disc after data is written to the detected region;   (b) while writing data to the optical disc, detecting if any defect exists on the optical disc according to reflection from the optical pickup head to thereby generate a first defect detecting result; and   (c) switching from one of the steps (a) and (b) to the other of the steps (a) and (b).   
     
     
         2 . The method of  claim 1 , wherein the step (a) further comprises generating a defect amount according to defects detected in the detected region; and the step (c) comprises:
 when the step (a) is currently performed for detecting defects on the optical disc, selectively switching from the step (a) to the step (b) according to the defect amount.   
     
     
         3 . The method of  claim 2 , wherein selectively switching from the step (a) to the step (b) according to the defect amount comprises:
 comparing the defect amount with a predetermined value; and   switching from the step (a) to the step (b) when the defect amount is less than the predetermined value.   
     
     
         4 . The method of  claim 3 , wherein the detected region includes a plurality of ECC (error correction code) blocks, and the step (a) accumulates ECC blocks each having at least a defect to generate the defect amount. 
     
     
         5 . The method of  claim 1 , further comprising:
 (d) detecting if any defect exists in a detected region that is already detected via the step (b) to generate a second defect detecting result;   (e) comparing the first defect detecting result and the second defect detecting result; and   (f) switching from the step (b) to the step (a) if a comparing result of the step (e) indicates that a difference between the first defect detecting result and the second defect detecting result reaches a threshold value.   
     
     
         6 . The method of  claim 1 , wherein the step (c) further comprises switching from the step (b) to the step (a) when data amount written to the optical disc exceeds a threshold value while performing the step (b). 
     
     
         7 . The method of  claim 1 , wherein the step (c) further comprises switching from the step (b) to the step (a) when a region where data to be written on the optical disc exceeds a threshold value or reaches a selected region while performing the step (b). 
     
     
         8 . The method of  claim 1 , wherein the step (c) further comprises switching from the step (b) to the step (a) when a writing speed changes while performing the step (b). 
     
     
         9 . The method of  claim 1 , wherein the step (c) further comprises switching from the step (b) to the step (a) if the step (b) is performed for a predetermined time. 
     
     
         10 . An optical disc defect detecting system, comprising:
 an optical pickup head arranged to access an optical disc;   a data error detector arranged to read data from a detected region of the optical disc and detecting if any data error exists after the data is written to the detected region;   a defect detector arranged to detect if any defect exists on the optical disc according to reflection from the optical pickup head to thereby generate a first defect detecting result, while writing data to the optical disc; and   a control unit arrange to switch the optical disc defect detecting system from one of a first mode and a second mode to the other of the first mode and the second mode;   
       wherein the optical disc defect detecting system utilizes the data error detector in the first mode and utilizes the first and the defect detector in the second mode. 
     
     
         11 . The optical disc defect detecting system of  claim 10 , wherein the data error detector is a decoder or a comparator. 
     
     
         12 . The optical disc defect detecting system of  claim 10 , wherein the control unit further generates a defect amount according to defects detected in the detected region, and the control unit selectively switches the optical disc defect detecting system from the first mode to the second mode according to the defect amount. 
     
     
         13 . The optical disc defect detecting system of  claim 12 , wherein the control unit compares the defect amount with a predetermined value, and switches the optical disc defect detecting system from the first mode to the second mode when the defect amount is less than the predetermined value. 
     
     
         14 . The optical disc defect detecting system of  claim 13 , wherein the detected region includes a plurality of ECC (error correction code) blocks, and the control unit accumulates ECC blocks each having at least a defect to generate the defect amount. 
     
     
         15 . The optical disc defect detecting system of  claim 10 , wherein the data error detector read data from the detected region to generate a second defect detecting result, where the control unit compares the first defect detecting result and the second defect detecting result to generate a comparing result and switches the optical disc defect detecting system from the second mode to the first mode if the comparing result indicates that a difference between the first defect detecting result and the second defect detecting result reaches a threshold value. 
     
     
         16 . The optical disc defect detecting system of  claim 10 , wherein the control unit further switches the optical disc defect detecting system from the second mode to the first mode when data amount written to the optical disc exceeds a threshold value. 
     
     
         17 . The optical disc defect detecting system of  claim 10 , wherein the control unit further switches the optical disc defect detecting system from the second mode to the first mode when a region where data to be written on the optical disc exceeds a threshold value or reaches a selected region. 
     
     
         18 . The optical disc defect detecting system of  claim 10 , wherein the control unit further switches the optical disc defect detecting system from the second mode to the first mode when a writing speed changes. 
     
     
         19 . The optical disc defect detecting system of  claim 10 , wherein the control unit further switches the optical disc defect detecting system from the second mode to the first mode when the optical disc defect detecting system operates in the second mode for a predetermined time.